Method for demodulating a carrier wave modulated by a digital symbol sequence

Abstract

A method for demodulating a carrier wave that is modulated using a digital symbol sequence and that is transmitted over a noise-impacted channel, the ideal edge shapes of possible transitions between two symbols being known and stored in memory as reference edges, and a received edge being scanned and digitalized using a scanning frequency that is a multiple of the frequency of the symbol sequence. In particular, for detecting a received and scanned edge, all scanning values are used for calculating Euclidean distances from at least two reference edges, and the reference edge associated with the lowest Euclidean distance is selected. A Viterbi algorithm is applied to a sequence of estimated edges (rather than to an estimated symbol sequence) and the specific Euclidean distances between the edge received in one symbol period and the reference edges are considered as the costs of one trellis branch of the Viterbi algorithm.

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